Friday, November 30, 2012

Freezing rain risk for parts of southern MB tonight..

A weather system over southern Saskatchewan will be pushing a warm front across southern Manitoba today into tonight, ushering a milder airmass from the south. Temperatures will be climbing towards the freezing mark overnight, especially closer to the US border. The milder weather however will also bring a threat of freezing rain or ice pellets tonight as the weather system track across southern MB. An area of freezing rain is expected to develop over southeast SK late today, and spread into SW Manitoba this evening. A freezing rain warning has been issued for these areas. This area of freezing rain may push into Winnipeg and the RRV overnight, however at this point, it appears the greatest risk is over SW Manitoba into parts of the interlake. This system will push east of southern MB Saturday morning, with drier and briefly cooler conditions in its wake.

UPDATE DEC 1st: TransCanada Highway is closed from Winnipeg to SK border this morning due to severe icing conditions. Travel not advised on many other roads in southern Manitoba, especially north and west of Winnipeg due to ice covered conditions from freezing rain overnight. For latest road and highway conditions, see Manitoba highways website.

Note also that radar images from the Weatheroffice website are now on SNOW rate and will overdo precipitation intensities during rainfall events. Consult Brad's radar viewer from A Weather Moment for radar images showing more accurate RAIN rate intensities during rain or freezing rain events in the winter (select 1.5 km CAPPI for RAIN rate).

Rain starting to blossom over eastern Montana spreading newd into SE Sask where surface temperatures are still below freezing. Result will be an area of freezing rain which will spread into SW MB this evening. GEM model looking like it had a good handle on this event...

Anonymous.. Monday looking more like a warm sector for Winnipeg with some rain or drizzle and above freezing temperatures initially, then turning colder with some light snow later Monday into Monday night. Better chance of heavier snow through interlake and western parklands. Haven't really looked much past Monday..

As noted, radar has switched over to snow rate on Weatheroffice. It was definitely supposed to switch over on Dec 3rd (Monday).. not sure why the date was pushed up. However, it was snowing in southern Ontario yesterday, and it wouldn't surprise me if that influenced their decision.

This just goes to highlight the problem of going with an "either/or" for radar typing. Canada is a big country, with a variety of climates. You can get rain in the winter, and snow in the fall and spring. Often, it will be raining in some parts of the country and snowing in others. That's why you need access to both rain AND snow rates for radar all the time, and just pick the one that is applicable for your location. You can do this from my radar page which uses Brad's radar viewer from A Weather Moment, but it sure would be nice if Weatheroffice could provide that option as well.

Nice and mild out there this morning with temperature above freezing in Winnipeg. Should stay above freezing through mid to late morning, then winds will shift into the NW and tap colder air to our north, with temperatures falling below freezing this afternoon, down to -5C by late afternoon. That will freeze up any standing water from this morning's melt.. so caution advised on untreated surfaces, especially by this evening.

That 17.0 mm of precipitation at YWG airport yesterday.. obviously an erroneous report since there was no precipitation yesterday other than some very light flurries. They may have been doing some maintenance on the gauge which resulted in the faulty reading, but it should not be accepted as a legitimate observation. Again, this highlights the problem of automated data going out without proper quality control.

Anonymous.. Yes, looks like we'll be in the warm sector of Monday's system with above freezing temps and some rain or drizzle. Turning colder by Monday evening, but heaviest snow remaining well north of Winnipeg.

Winds shifting to the NW in Winnipeg, temperatures will be dropping from here. According to Weatherfarm, temps are down to -1C in Stonewall right now, -3C in Elie, and -5C in Portage... so watch for temperatures falling below freezing in Winnipeg over the next hour or two.